Document FR-A-2 638 271 describes an example of such a light-emitting display panel, in which the front optical filter is substantially the same color as the light-emitting elements. Furthermore, in that display panel, an additional optical filter is interposed between the front optical filter and the opaque background, said additional optical filter being of a color that is complementary to the color of the front optical filter and being pierced by holes in register with the light-emitting elements.
That known display panel gives satisfaction since it is very legible, even in full sunlight, because of the large amount of contrast obtained between the light-emitting elements and the opaque background.
Nevertheless, that display panel suffers from the following drawbacks:
it is well adapted to monochrome light-emitting elements, but it is poorly adapted to displaying in a plurality of colors; and PA1 the additional optical filter is relatively expensive, insofar as it needs to be pierced with holes. PA1 the transmission coefficient of the front filter lies in the range 12% to 40% over substantially the entire visible light spectrum; PA1 the front optical filter is of a chestnut-brown color; PA1 the light-emitting elements are adapted to emit light mainly at a wavelength lying in the range 500 nm to 650 nm; PA1 the front face of the opaque background is black; PA1 the background is constituted by a plate carrying the light-emitting elements and which forms an electrical circuit for feeding power to said light-emitting elements; and PA1 the background comprises a mask pierced by holes disposed in register with the light-emitting elements, said mask forming the front face of the background.